Apple L. Raptor nest monitoring in the Great Divide Resource Area

Rawlins, WY: Bureau of Land Management, 1998. — 252 p.The Great Divide Resource Area's (GDRA) 1998 raptor monitoring and inventory was the most extensive and coordinated effort in more than 15 years. Six volunteers, recruited this spring, worked in two major areas. The first was the Shamrock Hills Area of Critical Environmental Concern (ACEC) west of Rawlins. Two volunteers intensively monitored and inventoried all raptors nesting within this area. The other major area was the Continental Divide/Wamsutter II Oil and Gas EIS Area (CD/WII) , located both north and south of Wamsutter. This latter area was divided into two monitoring units, one north and one south of Interstate 80 (1-80). Two volunteers were assigned to each area.
In addition to the general raptor monitoring, we monitored the activity at 91 artificial nesting structures (ANSs) built to attract ferruginous hawks (81 ANSs) , golden eagles (nine ANSs), and red-tailed hawks (one ANS) away from nests susceptible to human disturbance. The first 30 ANSs were constructed in 1987 and the remaining 61 have been added during the past 10 years.
The 1998 nesting activity of ferruginous hawks, golden eagles, and other raptors is difficult, if not impossible, to compare to 1997 nesting levels. This is because the scope of the 1998 monitoring was much expanded over that accomplished in 1997. Eight known and three newly -discovered natural golden eagle nests were active, as were two artificial nesting structures (ANSs) built specifically for golden eagles. Fourty- six ferruginous hawk pairs used ANSs (38 pairs successfully layed eggs and raised young and eight pairs failed to produce eggs or abandoned the nests prior to laying eggs) , two golden eagle ANSs were successfully used by ferruginous hawks, and 11 known and eight newly discovered natural ferruginous hawk nests were active (14 successful and 5 failures) . In total, we monitored 67 ferruginous hawk pairs attempting to nest within the Great Divide Resource Area. Fifty-four of these pairs successfully produced young.
Thirteen pairs failed to produce eggs, abandoned nests with eggs, or lost young and consequently abandoned their nests. It should be stressed that there are undoubtedly many more successful and unsuccessful ferruginous hawk nesting pairs within the GDRA outside the areas we were able to monitor.